For the great majority of small scale farming households in West Africa, labor is one of their most crucial factors of production. Yet, the dynamics behind these households' patterns of labor allocation are not well understood by planners and policy makers. This study argues that (a) a household's labor allocation behavior is determined by its real opportunity set vis-a-vis the household's basic objectives, (b) a household's real opportunity set is the sum of its main constraints and opportunities after all environmental dimensions have been simultaneously considered, (c) male and female household members do not have the same opportunity sets. The environmental circumstances of the Diola and Mandingized Diola farm households from the Casamance region of Senegal provide the quantitative foundation of the analysis. For each group, an opportunity set for an average household is derived with a special emphasis on gender differentiations. Based on these derived opportunity sets, a household's behavior regarding labor allocation is hypothesized. Hypothesized behaviors are then checked against observed behaviors of labor allocation. Among both groups, household labor allocation strategies seem to reflect a desire of farmers to use their comparative advantage to reduce the adverse effects of their main binding constraints. With respect to farmers' ability to fulfill their basic objectives, the Mandingized Diolas appear to be better off than the Diolas and within each group, men appear to be better off than women.